test: split test-runner-run-watch.mjs #739

Job	Run time
Build slim tarball	1m 35s
x86_64-linux: with shared libraries	2h 24m 32s
aarch64-linux: with shared libraries	2h 19m 45s
aarch64-darwin: with shared libraries	1h 46m 52s
x86_64-darwin: with shared libraries	52m 9s
	7h 24m 53s

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